Chapter 2 World Geography: Looking at the Earth. Section 1 Planet Earth Planet Earth.
Introduction to Planet Earth
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Transcript of Introduction to Planet Earth
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Introduction to Planet Earth
Let’s dig a hole to China!
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Earth Stats
• The Earth's mass is about 5.98 x 1024 kg.
• Earth is the densest planet in our Solar System (mass/volume).
• Earth is made of several layers with different compositions and physical properties, like temperature, density, and the ability to flow.
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The Composition of the Earth
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The Composition of the Earth
Crust• Thinnest layer (5-100 km)• Two types of crust
• Continental • Like granite• Average 30 km
• Oceanic• Like basalt
(Basalt is denser than granite!)• Average 5-8 km
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The Composition of the Earth
Mantle• Extremely Thick! (2,900 km)• It is too far down to drill
• How do we know what it is made of?
• Scientists infer based on:• Pushed up rock• Ocean floor/molten rock
• What is it like?• Like the mineral olivine
• Large amounts of iron and magnesium
www.soc.soton.ac.uk
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The Composition of the Earth
Core• Pretty darn big. (6,856 km)
• (Slightly bigger than Mars!)• 33% mass of the Earth
• Scientists think….• Made mostly of iron• Some nickel, sulfur, oxygen
• What is the evidence?• The particular way seismic
waves travel• Earth’s Magnetic field
N
S
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The Structure
of the Earth
Inner CoreSolid
Outer CoreLiquid
MesosphereSolid
AsthenosphereViscous Liquid
LithosphereSolid
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Asthenosphere = ‘weak sphere’Lower part of Mantle
Lithosphere = ‘rock sphere’Crust and upper rigid part of Mantle
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How HOT is it?
Surface of Sun! 5,500°CSun Core 15,000,000°C
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Convection• Convection (heat) currents
– carry heat from the hot inner mantle to the cooler outer mantle.
• The mantle gets warmer with depth • top of the mantle is ~ 1,600° F (870° C)• bottom of the mantle is ~4,000-6,700° F
(2,200-3,700° C) • The mantle contains most of the mass of
the Earth
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Let’s Make Models of the Earth!
• Inner Core (yellow) diameter 2 cm (4)• Outer core (orange) diameter 6 cm (4)• Mesosphere (red) diameter 11cm (4)• Asthenosphere (brown) diameter 12cm (2)• Lithosphere (sand)
– -after assembly roll edges of asthenosphere in glue and then sand (1.5mM thick)